Western South America: Ecuador and Peru

This ecoregion lies between Ecuador and Peru where it is limited by plant formations of mangrove (Rhizophora spp.) forest that occur at the confluence of many rivers emptying into the Pacific Ocean and the Gulf of Guayaquil. These forests are adapted to permanently flooded conditions and the resulting environments, which offer little available oxygen. A diversity of flora and fauna can be found in this mangrove ecoregion including ducks, herons, and woodpeckers as well as primates and iguanas.

Scientific Code

(NT1413)

Ecoregion Category

Neotropical

Size

1,300 square miles

Status

Critical/Endangered

Habitats

Description Location and General DescriptionThe mangrove forests of this ecoregion border the Gulf of Guayaquil, in Ecuador and the extreme northwestern Pacific Coast of Peru near Tumbes. The part of the ecoregion closest to the equator lies between parallels 3°24’ (Punta Capones) and 3°34’ 41’’ south latitude (Estero El Chalaco) and meridians 80°13’ 08’’ (Estero Hualtaco) and 80°31’ 53’’ east longitude (Estero La Chepa). The climate is semitropical with annual rainfall between 100 and 300 mm in contrast to south of parallel 5° south latitude where the Peruvian Coast becomes subtropical and desert-like due to the influence of the Humboldt Current. Average annual temperature in the zone is about 25 °C, varying between the extremes of 18 °C and 32 °C, from winter to summer. The mangroves of this ecoregion lie on continental deposits from the recent Quaternary; resulting soils consist of sands, clays, gravel and poorly consolidated stone such as muds and fine sediments.

In front of coasts that have mangrove communities there are often off shore islands. These originate from banks of mud and sand moved and deposited by the rivers and tides. These islands may eventually be colonized by mangrove-type vegetation (Rhizophoretum) and with the passage of years may become joined to the continent, to other larger islands or remain as they are (CDC 1997).

It was originally thought that there were four species present in the mangroves: Rhizophora mangle, Avicenia germanis (A. nitida), Laguncularia racemosa and Conocarpus erectus (Chapman 1980). Some authors believe that Conocarpus is not present in Ecuador (IUCN 1983). However, it has been found in limited areas within this ecoregion. Later taxonomic studies have revealed the presence of Rhizophora harrisonii and probably Rhizophora rapemosa (Parnier and Parnier 1980).

In some places where the accumulation of material has allowed the average level of the soil to rise, there are tree species such as Acacia macracantha and Prosopis chilensis and cacti such as Cereus cartwrighttianus and Armatocereus laetus (Ferreyra 1979 and 1959; ONERN 1976). This condition can even be found on some islands such as Isla del Amor and El Tanque. Towards dry land, the terrain rises gradually leading to different soil types and subsequent appearance of carob formations.

Biodiversity FeaturesThe fauna in the mangrove area is notable not only for its variety but also for its temporary presence at specific stages in its development, even dry forest species can be found in the mangrove forest at certain times. This is true of the white-winged guan (Penelope albipennis); its population status is precarious and it has most likely disappeared from the area. This bird was found on small "islands" of dry forest within the mangrove forest itself, produced by edaphic differences derived from a higher elevation of the terrain. Species also use the mangrove habitat as refuge when resources in neighboring areas are low. More than 50 species of migrant birds use this wetland ecoregion both as a stop over area and a winter destination.

Another case is the American crocodile (Crocodylus acutus) the population of which is very low in the mangroves and probably close to the minimum than can be tolerated while still maintaining its viability. It is in this ecoregion that it reaches it southern most latitudinal limit.

Characteristics species of fauna in the mangrove include the mantled howler monkey (Alouatta palliata), paca (Agouti paca), northern tamandua (Tamandua mexicana), crab-eating raccoon (Procyon cancrivorus) and the Mexican otter (Lutra longicaudis annectens). Also a great variety of tropical marine birds including rufescent tiger-heron (Tigrisoma lineatum), wood stork (Mycteria americana), and horned screamer (Anhima cornuta) are just a few species present in this ecoregion, not to mention invertebrates such as shrimp, crabs and mollusks.

Current StatusThe destruction of the mangroves for the production of wood is insignificant, due to the small forest area available for such purposes. Nonetheless, extensive areas have been cut for the construction of shrimp pools. It is estimated that nearly 50% of the area of the Tumbes mangrove forest, in Peru was cut between 1945 and 1985. Contamination of mangrove habitat is caused by the discharge of domestic, agricultural and industrial waste. However, the situation has not been sufficiently studied.

A state-protected area in this ecoregion is the Churute Mangroves Ecological Reserve, in Ecuador, which is located within the estuaries of the Churete and Taura Rivers. The principal mangrove species in this area are Rhizophora mangle (more than 80%), Conocarpus erectus and Avicennia nitida. The Tumbes Mangrove National Sanctuary (Peru) protects the only population of mangrove vegetation, in Peru.

Types and Severity of ThreatsThe activity that causes the greatest impact and poses the greatest threat on this ecoregion is transformation of mangrove habitat for sea farming, that has been developing since 1971 based on the growing of shrimp (Penaeus vannamei) for commercial purposes. Although current legislation prohibits cutting the mangrove trees, dikes and canals are being constructed through the woody masses of mangrove and may eventually alter the normal development of this ecosystem, causing them to die off. While there is not mining activity in the department of Tumbes. There are more than 10,000 people engaged in prospecting for and mining gold in the high basin of the Puyango River (Ecuador), which threatens mangroves with pollutants, and change in sediment load and the flow of freshwater into the mangroves.

Justification of Ecoregion DelineationClassification and linework for all mangrove ecoregions in Latin America and the Caribbean follow the results of a mangrove ecoregion workshop (1994) and subsequent report (Olson et al. 1996).